1. Field of the Invention
The present invention relates to an exhaust device of an internal combustion engine which is adapted to discharge the exhaust gas of the engine through an exhaust pipe.
2. Description of Background Art
A conventional exhaust device for an internal combustion engine is known wherein first and second partition-wall plates are disposed in a muffler to define first, second and third expansion chambers. Connection pipes are disposed to allow the first, second and third expansion chambers to communicate with each other. An acoustic absorption material is attached to the outer circumference of the connection pipe and the outer circumference of the acoustic absorption material is covered with punching metal. In this way, a reduction in exhaust sound is intended. See, for example, Japanese Patent Publication No. Hei 7-88771.
An exhaust device for an internal combustion engine is known wherein an expansion chamber is disposed on the exhaust downstream side of an exhaust gas collection portion where a plurality of exhaust pipes are assembled. In this way, the occurrence of a torque valley is suppressed. See, for example, Japanese Patent Laid-Open No. 2007-162653.
In addition, the exhaust devices of an internal combustion engine described in Japanese Patent Publication No. Hei 7-88771 and Japanese Patent Laid-Open No. 2007-162653 can achieve only one of a reduction in exhaust sound and the suppression of occurrence of a torque valley. Therefore, an exhaust device of an internal combustion engine that can achieve both is required.